The safety of the use of selective serotonin reuptake inhibitors (SSRIs) during pregnancy is a question of considerable importance to patients and clinicians. In humans, long-term effects on childhood behavioral outcomes after in utero exposure to SSRI drugs have not been extensively studied. The aim of the study is to examine the association between SSRI use during pregnancy and childhood/adolescent developmental and neuropsychiatric outcomes in offspring. The data are collected from four nationwide registers in Finland that include data on maternal SSRI use, pregnancy and infancy, congenital malformations, and inpatient and outpatient psychiatric diagnoses. All registers are mandatory, cover all Finnish citizens and permanent residents, and are maintained by national authorities. We shall use a prospective cohort study design and investigate the incidence of perinatal complications and neuropsychiatric outcomes in offspring exposed and unexposed to SSRIs in utero. The main definition of exposure is the use of one or more SSRI medications at any time during pregnancy. The unexposed cohort will be defined as offspring who were unexposed to SSRI's during pregnancy but in which the mother was treated with an SSRI up to 1 month before pregnancy. We will have identified 11,000 children exposed in utero to SSRIs from 1996-2010. Offspring will be followed up until 2012; hence the age range of the sample will be from birth to age 16. Outcomes include: perinatal complications and several childhood/adolescent neuropsychiatric outcomes (ICD-10 criteria). We expect that the study will provide the first epidemiologic evidence of the potential consequences of SSRIs on childhood developmental and neuropsychiatric outcomes. In addition to having considerable implications for prescribing practices for clinicians, the present project will augment, and be augmented by, the other projects in the Center in several respects, within the framework of an international collaboration.